Some conventional fingerprint scanners include large, wall-mounted units, called contact or placement sensors, that sense an entire fingerprint at once (e.g., an entire fingerprint including images of 200-500 rows and 128-200 columns of pixels). Other fingerprint scanners include smaller swipe scanners incorporated into laptop and notebook computers, mobile phones, mobile email devices, and smart phones. Smaller swipe scanners are much less expensive to manufacture than larger contact or placement scanners. Stationary swipe fingerprint scanners sense a finger being swiping across the scanner and can be dual line scanners or multi line scanners.
One example of a dual line scanner is disclosed in U.S. Pat. No. 6,002,815 issued to Immega et al. on Dec. 14, 1999 (“Immega”), the entire contents of which is herein incorporated by reference. The Immega dual line scanner must determine and track the velocity of the finger as it passes over the sensor and a 1×n pixel array scanner. The Immega dual line scanner performs 1×n linear array cross-correlation on current and historic line scans to initially image the fingerprint. The velocity of the finger must then be known in order to reconstruct the fingerprint image from the line scans.
One example of a multi-line scanner is disclosed in U.S. Pat. No. 7,197,168, issued to Russo on Mar. 27, 2007 (“Russo”), the entire contents of which is herein incorporated by reference. The Russo multi line scanner reassembles overlapping object imaging frame scans collected by a multi-line sensor array to reconstruct the fingerprint image without calculating the velocity of the finger.